1. Field of the Invention
This invention relates to certain benzoheterocyclic compounds and to pharmaceutically acceptable salts thereof which are useful as antimicrobial agents, processes for preparing the same, the pharmaceutical compositions containing the benzoheterocyclic compound or salts thereof.
2. Description of the Prior Art
It is known that certain types of polyheterocyclic compounds exhibit antimicrobial activities. For example, U.S. Pat. No. 3,917,609 to Gerster et al. discloses substituted derivatives of 1,2-dihydro-6-oxo-6H-pyrrolo-[3,2,1-ij]quinoline which are useful as antimicrobial agents or as intermediates for the preparation of antimicrobial agents.
Also, U.S. Pat. Nos. 3,896,131, 3,985,882, 3,969,463, 4,001,243 and 4,014,877 to Gerster et al. GB-A-2057440 and Japanese Patent Application (OPI) No. 30964/81 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") disclose 6,7-dihydro-1-oxo-1H,5H-benzo[ij]quinolizine derivatives having antimicrobial activities.
Further, GB-A-2020279 describes 6,7-dihydro-1-oxo-1H,5H-benzo[ij]quinolizine-2-carboxylic acid derivatives and 1,2-dihydro-6-oxo-6H-pyrrolo[3,2,1-ij]quinoline-5-carboxylic acid derivatives having antibacterial activities, and 1,2-dihydro-6-oxo-6H-pyrrolo[3,2,1-ij]quinoline-5-carboxylic-5-carboxylic acid derivatives having antibacterial activities.
However, the benzoheterocyclic compounds of the present invention are structurally different from such quinoline and quinolizine compounds.